scholarly journals Interstellar scintillation observations for PSR B0355+54

2018 ◽  
Vol 476 (4) ◽  
pp. 5579-5590 ◽  
Author(s):  
Y H Xu ◽  
K J Lee ◽  
L F Hao ◽  
H G Wang ◽  
Z Y Liu ◽  
...  
Keyword(s):  
Interstellar Scintillation

scholarly journals The presence of interstellar scintillation in the 15 GHz interday variability of 1158 OVRO-monitored blazars

2019 ◽  
Vol 489 (4) ◽  
pp. 5365-5380 ◽  
Author(s):  
J Y Koay ◽  
D L Jauncey ◽  
T Hovatta ◽  
S Kiehlmann ◽  
H E Bignall ◽  
...  
Keyword(s):  
Flux Density ◽  
High Energy ◽  
Short Term ◽  
Owens Valley ◽  
Hot Stars ◽  
Radio Observatory ◽  
Interstellar Scintillation ◽  
The Galaxy ◽  
Rare Class

ABSTRACT We have conducted the first systematic search for interday variability in a large sample of extragalactic radio sources at 15 GHz. From the sample of 1158 radio-selected blazars monitored over an ∼10 yr span by the Owens Valley Radio Observatory 40-m telescope, we identified 20 sources exhibiting significant flux density variations on 4-d time-scales. The sky distribution of the variable sources is strongly dependent on the line-of-sight Galactic H α intensities from the Wisconsin H α Mapper Survey, demonstrating the contribution of interstellar scintillation (ISS) to their interday variability. 21 per cent of sources observed through sightlines with H α intensities larger than 10  rayleighs exhibit significant ISS persistent over the ∼10 yr period. The fraction of scintillators is potentially larger when considering less significant variables missed by our selection criteria, due to ISS intermittency. This study demonstrates that ISS is still important at 15 GHz, particularly through strongly scattered sightlines of the Galaxy. Of the 20 most significant variables, 11 are observed through the Orion–Eridanus superbubble, photoionized by hot stars of the Orion OB1 association. The high-energy neutrino source TXS 0506+056 is observed through this region, so ISS must be considered in any interpretation of its short-term radio variability. J0616−1041 appears to exhibit large ∼20 per cent interday flux density variations, comparable in magnitude to that of the very rare class of extreme, intrahour scintillators that includes PKS0405−385, J1819+3845, and PKS1257−326; this needs to be confirmed by higher cadence follow-up observations.

scholarly journals The Microarcsecond Quasar J1819+3845

2001 ◽  
Vol 205 ◽  
pp. 88-89 ◽  
Author(s):  
J. Dennett-Thorpe ◽  
A. G. de Bruyn
Keyword(s):  
Scattering Medium ◽  
Short Term ◽  
Peculiar Velocity ◽  
Interstellar Scintillation

We present new WSRT observations of the micro-arcsecond quasar J1819+3845. All short term variations are attributed to interstellar scintillation of a source which is at most 30 micro-arcseconds in diameter. The timescale of the modulations changes over the year, which we interpret as due to a peculiar velocity of the scattering medium. The scintillation behaviour can be used to determine sub-structure in the source.

scholarly journals Interstellar Scintillation and Intraday Variability

1998 ◽  
Vol 164 ◽  
pp. 269-270
Author(s):  
Barney J. Rickett
Keyword(s):  
Intrinsic Variability ◽  
Brightness Temperatures ◽  
Interstellar Scintillation ◽  
Intraday Variability

AbstractSources that are compact enough to show intrinsic variability on times of a day or less (IDV) at cm wavelengths must also show interstellar scintillation (ISS) on similar timescales. However for many IDV sources, the variations could be entirely due to ISS, reducing the implied brightness temperatures to ~ 1013 K or less.

scholarly journals Strong, Variable Circular Polarization in PKS 1519–273

2001 ◽  
Vol 182 ◽  
pp. 135-138
Author(s):  
Jean-Pierre MacQuart ◽  
Lucyna Kedziora-Chudczer ◽  
David Jauncey ◽  
David Rayner
Keyword(s):  
Brightness Temperature ◽  
Frequency Dependence ◽  
Radio Source ◽  
Circular Polarization ◽  
Stokes Parameters ◽  
Variable Component ◽  
Circularly Polarized ◽  
Interstellar Scintillation ◽  
Variable Radio ◽  
Variable Radio Source

AbstractWe find strong (> 1%) circular polarization in the intraday-variable radio source PKS 1519–273. The source exhibits ~ 12 hourly variability in all four Stokes parameters at 4.8 and 8.6 GHz, and longer timescale variability at 2.5 and 1.4 GHz. The characteristics and frequency dependence of the variability suggest that it is due to interstellar scintillation. VSOP limits on the distance to the scattering screen constrain the brightness temperature to TB > 5 × 1013 K. The fluctuations in total intensity are well-correlated with those in circular polarization, implying that the variable component of the source is −3.8 ±0.4% circularly polarized at 4.8 GHz. The origin of the circular polarization is unclear.

A Multi-Purpose, Multi-Channel Radiospectrograph for the Parkes Telescope

1987 ◽  
Vol 7 (2) ◽  
pp. 197-204 ◽  
Author(s):  
J. Lim ◽  
G. J. Nelson ◽  
A. E. Vaughan
Keyword(s):  
Large Scale ◽  
Second Harmonic ◽  
Plasma Radiation ◽  
Spectral Studies ◽  
Scientific Objective ◽  
Interstellar Scintillation ◽  
Peak Flux ◽  
Flare Stars ◽  
Under Construction ◽  
Compact Sources

AbstractThe design and scientific applications of a 96-channel filter spectrograph of 1 MHz resolution are presented. The spectrograph is currently under construction and will be installed on the Parkes telescope in 1987-1988. Its main scientific objective is dynamic spectral studies of decimetre- and metre-wavelength bursts from flare stars. However, it will also be used for performing large-scale pulsar surveys, and dynamic spectral observations of interplanetary scintillation of compact sources, interstellar scintillation of compact extragalactic sources, and interesting radio sources in general.We show that plasma emission generated in the coronae of flare stars should be detectable at metre- and decimetre-wavelengths. We plan to search for fundamental and second-harmonic plasma radiation by observing in two harmonically related bands, 200 to 250 MHz and 400 to 500 MHz. With noise-adding to stabilize receiver gain, the sensitivity (3σ) of each channel of the spectrograph is ∼ 1.5 Jy for a 1-s integration. Previous studies have reported peak flux densities of up to ∼ 35 Jy and ∼ 12 Jy at 240 MHz and 410 MHz respectively for radio bursts from flare stars.

scholarly journals Daily observations of interstellar scintillation in PSR B0329+54

2008 ◽  
Vol 385 (3) ◽  
pp. 1393-1401 ◽  
Author(s):  
N. Wang ◽  
Z. Yan ◽  
R. N. Manchester ◽  
H. X. Wang
Keyword(s):  
Interstellar Scintillation

scholarly journals The Size of IDV Jet Cores

2002 ◽  
Vol 19 (1) ◽  
pp. 55-59 ◽  
Author(s):  
T. Beckert ◽  
T. P. Krichbaum ◽  
G. Cimò ◽  
L. Fuhrmann ◽  
A. Kraus ◽  
...  
Keyword(s):  
Function Analysis ◽  
Large Fraction ◽  
Electron Population ◽  
Interstellar Scintillation ◽  
Spectrum Radio ◽  
Shock Models ◽  
Cold Electrons ◽  
Time Argument ◽  
Local Cloud ◽  
Size Estimates

AbstractRadio variability on timescales from a few hours to several days in extragalactic flat spectrum radio sources is generally classified as intraday variability (IDV). The origin of this short term variability is still controversial and both extrinsic and intrinsic mechanisms must be considered and may both contribute to the observed variations. The measured linear and circular polarisation of IDV sources constrains the low energy end of the electron population. Any population of cold electrons within sources at or above the equipartition temperature of 1011 K depolarises the emission and can be ruled out. Intrinsic shock models are shown to either violate the large fraction of sources displaying IDV or they do not relax the light travel time argument for intrinsic variations. From structure function analysis, we further conclude that interstellar scintillation also leads to tight size estimates unless a very local cloud in the ISM is responsible for IDV.

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